Three dimensional (3D) printing technology by direct ink writing (DIW) is an innovative complex shaping technology, possessing advantages of flexibility in fabrication, high efficiency, low cost, and environmental-friendliness. Herein, 3D printing of complex alumina ceramic parts via DIW using thermally induced solidification with carrageenan swelling was investigated. The rheological properties of the slurry under different thermally-induced modes were systematically studied. The solidification properties of thermally-induced pastes with varying contents of carrageenan were optimized. The experimental results showed that the optimized paste consisting of 0.4 wt% carrageenan could be rapidly solidified at about 55 °C, which could print inclined-plane more than 60° in vertical without support, resulting in better homogeneity of the green body. A nearly pore-free structure was obtained after sintering at 1600 °C for 2 h.

A zirconium and a zirconium/boron containing single‐source precursor were synthesized via chemical modification of a commercially available polysilazane (Durazane 1800) with tetrakis (dimethylamido) zirconium (IV) (TDMAZ) as well as with both TDMAZ and borane dimethyl sulfide complex, respectively. The polymer‐to‐ceramic transformation of the precursors into SiZrCN and SiZrBCN ceramics as well as the thermal evolution of their phase composition and microstructure was studied. The pyrolysis of the precursors led to the formation of amorphous SiZrCN and SiZrBCN ceramics. Interestingly, the as prepared SiZrBCN ceramic was single‐phasic and fully featureless; whereas SiZrCN exhibited the presence of nano‐sized ZrO ₂ particles; however, only very localized in close proximity to internal surfaces. Heat treatment at higher temperatures induced crystallization processes in both prepared ceramics. Thus, at temperatures beyond 1500°C, cubic ZrC _x N _y , β‐Si ₃ N ₄ as well as β‐SiC were generated. It was shown that the incorporation of B into SiZrCN suppressed the crystallization of ZrC _x N _y and, in addition, impeded the reaction of SiN _x with C, resulting in an improved thermal stability of SiZrBCN compared to SiZrCN ceramic. Moreover boron was shown to be mainly located in the sp ² ‐hybridized “free” carbon present in SiZrBCN, forming a turbostratic BCN phase which has been unequivocally detected by means of high‐resolution transmission electron microscopy (HRTEM) and energy‐dispersive X‐ray spectroscopy (EDS).

ZrB₂-SiBCN ceramics with ZrO₂additive are hot-pressed under a constant applied pressure. The densification behavior of the composites is studied in a view of creep deformation by means of the Bernard-Granger and Guizard model. With determination of the stress exponent (n) and the apparent activation energy (Q_d), the specific deformation mechanisms controlling densification are supposed. Within lower temperature ranges of 1300–1400 °C, the operative mechanism is considered to be grain boundary sliding accommodated by atom diffusion of the polymer-derived SiBCN (n= 1,Q_d= 123±5 kJ/mol) and by viscous flow of the amorphous SiBCN (n= 2,Q_d= 249±5 kJ/mol). At higher temperatures, the controlling mechanism transforms to lattice or intra-granular diffusion creep (n= 3–5) due to gradual consumption of the amorphous phase. It is suggested that diffusion of oxygen ions inside ZrO₂into the amorphous SiBCN decreases the viscosity, modifies the fluidity, and contributes to the grain boundary mobility.

The electronic structure and optical properties of oxygen vacancy and La-doped Cd ₂ SnO ₄ were calculated using the plane-wave-based pseudopotential method based on the density functional theory (DFT) within the generalized gradient approximation (GGA).